Moonless twilight may cue mass spawning

Sentimental songs aside, maybe it’s an absence of moonlight that turns the bounding main into a sea of love.

On evenings when the moon lags below the horizon after sunset, twilight takes on an especially blue cast. That color shift, intensifying on nights after the full moon, might cue the remarkably synchronized mass spawning of some marine species, suggests Alison Sweeney of the University of California, Santa Barbara.

Corals, perhaps the most famous of the mass spawners, don’t have central nervous systems or actual eyes. Yet many corals manage to release their eggs and sperm into the water o

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